It is programmed to pick up typical language used by sex predators when grooming children.

Michele Elliott, of children's charity Kidscape, which has tried out the device, welcomed the peace of mind the device would bring to families wanting to protect their children from paedophiles prowling the internet.

She said: "Parents are right to be concerned that paedophiles are using the internet to groom children.

"The XGate offers protection for children and gives parents a way to monitor or shut down activity that could be dangerous.

"We want children to be able to use the internet safely and so we welcome this new technology."

Seona Shand, of Scottish children's charity Children 1st, said her charity was very excited by the product.

She said: "We're very excited by this technology. We're always looking for new ways of helping to protect children from the online threat of paedophiles.

"With technology advancing at such a rapid pace and children becoming more technologically minded, we need to keep up.

"This device allows parents to protect their children in a computer environment they may not be used to."

The XGate differs from traditional home computer security in that it is not a piece of software that sits on the PC and slows it down.

It plugs into the PC and includes an ADSL modem that allows users to browse the internet as fast as the connection allows.

The security device, made by Manchester-based company Global Security One (GSEC1), is on sale for £99.95.